Field of the Invention
The present invention relates to a method for manufacturing a cord included rubber sheet such as a chafer formed by coating a plurality of cords with rubber.
Description of the Related Art
A pneumatic radial tire in FIG. 5 is provided with a chafer 10 which is a reinforcing member for a tire. The chafer 10 is a cord included rubber sheet formed by coating a plurality of cords with rubber. The chafer 10 is generally disposed so as to pinch a carcass ply 8 from an inner side in a tire width direction over an outer side, as shown in FIG. 5. With this structure, an increase in strain created in an end portion 8E of the carcass ply 8 is suppressed. As a result, generation of separation beginning at the end portion 8E is prevented, and thus durability is improved. However, in the case where strain created in an end portion 10E of the chafer increases, separation may be generated beginning at the end portion.
As shown in FIG. 6, a cord 10C is exposed in the end portion 10E of the chafer, and it is known that the exposure becomes a factor for increasing strain. Therefore, there has been conventionally a case where the cord 10C is coated by attaching a rubber sheet 9 in order to suppress the increase in the strain created in the end portion 10E. However, use of an additional member such as the rubber sheet 9 increases a tire weight, and further deteriorates a rolling resistance of the tire. This tendency is particularly evident in the tire for a passenger car.
Patent Document 1 discloses a step of cutting a band-like carcass ply raw material into a predetermined length; however, a cord is not exposed to a cut surface. Patent Document 2 discloses a method for cutting a band-like member in which a textile cord is buried, but does not suggest a solution to the problem relating to the exposure of the cord. Patent Document 3 discloses a method for cutting a raw material band-like member by pressing a die surface inclined at a shallow angle; however, it is difficult to cut a cord included rubber sheet according to this method. (refer to paragraphs 0003 and 0004 in Patent Document 2).